App Fade animation in 4.0

I've started to notice what I think is a new animation in 4.0. Sometimes when I minimize an app it won't zoom out and fade. It just fades away. There's no zooming at all. I've been running the GM for weeks and I just noticed this starting to occur in the last few days. I think it's because of the availability of compatible apps. This fade doesn't always happen but I think when it does happen it's because of a low memory situation. In 3.0 and lower, especially on jailbroken phones, the zoom out animation would stutter quite noticably when the phone was strained. I think this is a little UI tweak to avoid that.

Anyone else noticed it on a 3GS? Since it may be low memory related it may not present itself on the 4 very often.